Notice that Maria has not chosen the rotated square, even though the poster shows a square, and similarly, she has left out the irregular pentagon, the irregular hexagon, and several of the triangles. She appears to associate the words with the specific examples she has seen on the poster, rather than having a general understanding of the shape names. She is probably unfamiliar with parallelograms.

Rosalio: My group is shapes with corners bigger than a square corner. On these shapes, I can hold the corner of a piece of paper over a big corner, and some of it sticks out, so I know that the corner is bigger than a square corner.

Notice that Rosalio has not chosen the obtuse triangles or the parallelogram. Also, notice that he is able to use his own language, rather than formal terms, such as obtuse and right angle, to communicate his understanding of the concept of obtuse angles.

Lucas: My group is triangles. I can tell that these have three sides and look like triangles.

Notice that Lucas has not chosen the two triangles that do not have a base parallel to the bottom of the page. He may know the attributes of a triangle but has a misconception about how the triangle must be oriented in space. Or, he may be using visual memory of past experiences with triangles on worksheets.